Combustion chamber for the incineration of waste products

ABSTRACT

A combustion chamber for use in the incineration of waste products includes an inner refractory wall which extends vertically within an outer protective wall in a spaced relationship so as to define a plenum therebetween. The inner refractory wall is constructed using a plurality of precast, refractory blocks which are stacked and arranged to define a cylindrical interior cavity. The refractory blocks include mating features on adjacent surfaces to facilitate assembly and provide structural support. For additional support, selected blocks are fixedly connected to vertical support tubes by metal tie-back anchors. To facilitate combustion, a selection of the blocks is precast with a tuyere hole in order to deliver a uniform and balanced supply of air from the plenum into the interior cavity. The precast nature of the refractory blocks enables the inner refractory wall to be constructed with great precision, thereby optimizing incineration and minimizing material degradation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. 119(e) toU.S. Provisional Patent Application No. 62/954,721, which was filed onDec. 30, 2019 in the names of Lee Rollins, Jr., et al., the disclosureof which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to waste disposal and, moreparticularly, to combustion chambers utilized to incinerate wasteproducts.

BACKGROUND OF THE INVENTION

A combustion chamber, or cell, is a well-known structure that iscommonly used to incinerate waste products through the application ofintense heat, which is typically in excess of 1000° C. For instance,wood production facilities often utilize a combustion cell to dispose ofwood waste, such as sawdust and bark, created from the manufacture ofwood-based products.

The heat generated by combustion chambers can, in turn, be utilized in awide range of additional applications. For instance, in wood-basedproduct manufacturing, the heat produced by combustion chambers is oftenused in the drying of finished, wood-based products. Heat produced fromcombustion chambers is also commonly applied to water to produce steam,which is subsequently used for, inter alia, district heating, hot watergeneration, and the generation of electricity by turbine generator.

Conventionally, a combustion cell is constructed as an enlarged,tower-like, chamber which includes an inner cylindrical wall thatextends vertically within an outer wall, the inner wall being spaced infrom the outer wall so as to define a plenum therebetween. The innerwall defines an enlarged, cylindrical interior cavity, or combustionzone, with an opening, or gas outlet, at its top end through which heatfrom the combustion zone escapes. A combustion grate is typicallymounted at the bottom of inner wall and serves to support the wasteproducts intended for incineration. An externally-accessible chutepenetrates through both outer and inner walls at a downward angle andinto communication with the combustion zone, thereby allowing for thedelivery of waste product into the interior cavity.

As previously noted, a plenum is established between the outer and innerwalls and allows for the delivery of air into the combustion zone tofacilitate the incineration process. The primary supply of air forcombustion is delivered into the interior cavity through the combustiongrate. As a secondary source of air into the combustion zone, a seriesof small nozzles, or tuyere holes, generally circular in transversecross-section, extend radially through the inner wall and therebyestablish a fluid communication path between the plenum and the interiorcavity. As can be appreciated, the number, arrangement, geometricconfiguration, openness, and angle of orientation of the nozzles allcontribute to the effectiveness in maintaining efficient combustion ofwood waste within the interior cavity.

Due to the intense heat generated within the combustion zone, it isrequired that the inner wall be constructed of a suitable heat-resistantmaterial. Traditionally, the inner wall is constructed using acylindrical, expanded metal (i.e. perforated) backbone, or support,which is welded in place. A unitary refractory liner is then appliedonto the interior of the expanded metal support.

The refractory liner is typically constructed of a heat-resistantmaterial that is initially deformable but eventually hardens through acuring process. For instance, refractory liner may be constructed ofeither a heat-resistant moldable refractory that is compacted withpneumatic tools onto the inner surface of the expanded metal support ora concrete-based mixture that is cast-in-place or shotcrete against theinner surface of the expanded metal support.

Prior to or during installation, tubular sleeves, often constructedusing polyvinyl chloride (PVC) piping or wooden dowels, are placedwithin the boundaries of the lining to act as form blanks to create thenozzle openings. Additionally, the deformable nature of the pre-curedrefractory liner allows for its penetration through the perforations inthe expanded metal support and thereby form a means of interconnection.Upon curing of the refractory liner, the tubular sleeves are removedfrom the refractory liner to yield the plurality of airflow nozzles usedto supplement the delivery of air into the combustion zone.

The refractory liner of a combustion chamber is subjected to variousforms of attack which can compromise its integrity. In particular, acombustion cell utilized to incinerate wood-based products continuouslysubjects the refractory liner to heat, abrasion, and alkali attack.These various factors often cause the refractory liner to degrade overtime, resulting in a number of harmful effects.

As a first effect, degradation of the refractory liner can change thegeometry of the airflow nozzles, resulting in nozzles becoming blockedwith ash and constricting, or even reversing, the designated airflow. Asa consequence, combustion often becomes stifled and airflow velocityincreases which, in turn, produces refractory liner abrasion and createsunbalanced combustion within the interior cavity that can acceleratedegradation in the liner in certain areas.

As a second effect, degradation of the refractory liner, particularlydue to alkali attack caused by the combustion of wood, can result in itsdestabilization, since the expanded metal backbone only affords limitedstructural support to the liner. Structural destabilization of therefractory liner renders it increasingly susceptible to cracking andexpansion-related failure, often rendering a combustion chamberinoperable until the refractory liner is suitably repaired or completelyreplaced.

As a third effect, degradation of the refractory liner exposes theexpanded metal support to a greater amount of heat. Because thermalexpansion of the metal support occurs at a greater rate than therefractory lining, the combustion chamber is rendered more susceptibleto accelerated failure.

SUMMARY OF THE INVENTION

In view thereof, it is an object of the present invention to provide anovel combustion chamber for the incineration of waste products.

It is another object of the present invention to provide a combustionchamber of the type as described above which is durable and experiencesminimal material degradation.

It is yet another object of the present invention to provide acombustion chamber of the type as described above which is designed todeliver a uniform and balanced supply of air in order to combust wasteproducts in an efficient manner.

It is still another object of the present invention to provide acombustion chamber of the type as described above which is inexpensiveto manufacture, can be installed with great precision, and is easy tomaintain.

Accordingly, as one feature of the present invention, there is provideda combustion chamber for the incineration of waste products, thecombustion chamber comprising (a) an outer protective wall, and (b) aninner refractory wall extending within the outer protective wall, theinner refractory wall being shaped to define an interior cavity, (c)wherein the inner wall comprises a plurality of precast, refractoryblocks.

Various other features and advantages will appear from the descriptionto follow. In the description, reference is made to the accompanyingdrawings which form a part thereof, and in which is shown by way ofillustration, an embodiment for practicing the invention. The embodimentwill be described in sufficient detail to enable those skilled in theart to practice the invention, and it is to be understood that otherembodiments may be utilized and that structural changes may be madewithout departing from the scope of the invention. The followingdetailed description is therefore, not to be taken in a limiting sense,and the scope of the present invention is best defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference numerals represent like parts:

FIGS. 1(a) and 1(b) are front perspective and front plan views,respectively, of a combustion chamber constructed according to theteachings of the present invention, the combustion chamber being shownin longitudinal cross-section to illustrate certain novel featuresrelating to its construction;

FIG. 1(c) is a simplified top section view of the combustion chambershown in FIG. 1(b), taken along lines 1(c)-1(c);

FIG. 2 is a top perspective view of a precast block set utilized in theassembly of the inner refractory wall shown in FIG. 1(a);

FIGS. 3(a)-(c) are inner perspective, right end perspective, and topplan views, respectively, of the long refractory block shown in theprecast block set of FIG. 2;

FIG. 3(d) is a section view of the long refractory block shown in FIG.3(c), taken along lines 3(d)-3(d);

FIGS. 4(a) and 4(b) are inner perspective and top plan views,respectively, of the short refractory block shown in the precast blockset of FIG. 2;

FIG. 4(c) is a section view of the short refractory block shown in FIG.4(b), taken along lines 4(c)-4(c);

FIGS. 5(a) and 5(b) are inner perspective and top plan views,respectively, of the short refractory block shown in the precast blockset of FIG. 2;

FIG. 5(c) is a section view of the short refractory block shown in FIG.5(b), taken along lines 5(c)-5(c);

FIGS. 6(a)-6(c) are inner, right end perspective. Inner, left endperspective, and outer, right end perspective views, respectively, ofthe tuyere refractory block shown in the precast block set of FIG. 2;

FIGS. 6(d) and 6(e) are longitudinal and lateral section views,respectively, of the tuyere refractory block shown in FIG. 6(a), thefigures being shown in section to illustrate the shape and orientationof the tuyere hole;

FIG. 7 is a top perspective view of the tieback refractory block shownin the precast block set of FIG. 2, the tieback refractory block beingshown exploded form with a tie-back anchor and a support tube;

FIG. 8 is a lateral section view of the tieback refractory block shownin FIG. 7, the tieback refractory block being shown welded to thesupport tube by the tie-back anchor;

FIG. 9 is an enlarged, fragmentary view of the inner refractory wallshown in FIG. 1(c); and

FIG. 10 is an enlarged, fragmentary, longitudinal section view of twolayers of the inner refractory wall shown in FIG. 1(a).

DETAILED DESCRIPTION OF THE INVENTION Combustion Chamber 11

Referring now to FIGS. 1(a), 1(b), and 1(c), there is shown a combustionchamber designed for the incineration of waste products, the combustionchamber being constructed according to the teachings of the presentinvention and identified generally by reference numeral 11. As will beexplained further in detail below, combustion chamber 11 is constructed,in part, using a plurality of precast, modular, refractory blocks whichare stacked and arranged with great precision to create an innerrefractory wall which is durable, experiences minimal materialdegradation, and delivers a uniform and balanced supply of air forincineration.

In the description that follows, combustion chamber 11 is referenced asbeing primarily designed for use in the incineration of wood-based wasteproducts. However, it should be noted that the present invention is notlimited for use in the incineration of wood-based waste products.Rather, it is to be understood that the principles of the presentinvention could be similarly applied to combustion chambers used in theincineration of a variety of different types of waste products.

As can be seen, combustion chamber 11, also referred to hereininterchangeably as combustion cell 11 or combustion unit 11, isconstructed as an enlarged, tower-like structure which includes an innerrefractory wall 13 which extends vertically within an outer protectivewall, or frame, 15. Inner wall 13 is spaced slightly in from outer wall15 so as to define a plenum 17 therebetween. As will be explainedfurther below, plenum 17 is provided to allow for the delivery of airused in the incineration process.

Inner refractory wall 13 is shaped to define an enlarged, generallycylindrical interior cavity, or combustion zone, 19. Inner wall 13 isadditionally shaped to define an opening, or gas outlet, 21 at the topof interior cavity 19 to allow for the escape of heat generated duringincineration. Although not limited to any particular application, it isto be understood that heat exiting through opening 21 may be utilizedfor one or more designated purposes, such as wood drying treatments.

A combustion grate 23 is mounted on inner refractory wall 13 at thebottom of interior cavity 19. Grate 23 is designed to support the wasteproducts intended for incineration and is preferably constructed of asuitable material, such as a water-cooled metal. A door-enclosableaccess port 25, approximately 19 inches in height, is formed in innerwall 13 proximate grate 23 to allow for the periodic cleaning,maintenance, and/or repair of the interior of combustion unit 11 whennot in active operation.

Combustion chamber 11 is provided with an externally-accessible deliverychute 27 which penetrates through inner and outer walls 13 and 15 at adownward angle and into communication with combustion zone 19. Arotatable worm drive 29 is disposed within delivery chute 27. As can beappreciated, waste products are preferably deposited into chute 27through enlarged exterior opening 27-1 and delivered by worm drive 29into interior cavity 19 for subsequent incineration.

In use, intense heat, often in excess of 1000° C., is applied in theregion directly above grate 23, this region being referenced herein asreactive fuel bed 31. To accelerate incineration, a uniform and balancedsupply of air is preferably delivered into combustion zone 19. A primarysupply of air used to fuel combustion is delivered upward through grate23 from a cylindrical air space 33 located directly beneath grate 23,space 33 being in direct communication with plenum 17. A secondarysupply of air used to fuel combustion is preferably delivered intointerior cavity through a plurality of airflow nozzles, or tuyere holes,35 which are formed in an optimal configuration within inner refractorywall 13 to ensure balanced airflow delivery, the particular details oftuyere holes 35 to be described in detail further below.

As can be appreciated, the unique construction of inner refractory wall13 provides construction chamber 11 with a number of notable advantagesover traditional combustion cells. Most notably, inner refractory wall13 of combustion chamber 11 is constructed, in part, using a refractoryblock set 101 of the type as shown in FIG. 2. As can be seen, refractoryblock set 101 is comprised of multiple varieties of modular, refractoryblocks, which can be selected and stacked in a predefined arrangement toconstruct inner wall 13. As can be appreciated, the precast and modularnature of the refractory blocks in set 101 serves not only to facilitateassembly and, if necessary, replacement but also to ensure constructionwith great accuracy and precision, particularly with respect to thelocation, geometric shape and angle of orientation of tuyere holes 35,which is a principal object of the present invention.

Refractory Block Set 101

As seen in FIG. 2, refractory block set 101 is shown comprising a longrefractory block 111, a short refractory block 131, a medium-lengthrefractory block 151, a tuyere refractory block 171 and a tiebackrefractory block 191. As can be appreciated, blocks 111, 131, 151, 171,and 191 serve as the foundational pieces, or building blocks, which areselected and arranged into stacked circular levels to form uniform innerwall 13.

It should be noted that the particular number and arrangement of each ofblocks 111, 131, 151, 171, and 191 are preferably selected by anengineer based on the desired dimensions of inner wall 13 as well as theintended application. Accordingly, the particular arrangement of blocks111, 131, 151, 171, and 191 shown in combustion chamber 11 is providedfor illustrative purposes only and modifications could be readilyimplemented thereinto without departing from the spirit of the presentinvention.

Additionally, it should be noted that refractory block set 101 couldinclude additional modular refractory blocks designs, not shown herein,without departing from the spirit of the present invention. As can beappreciated, the greater number of available refractory block shapes andstyles serves to enhances the flexibility in optimizing theconfiguration of inner refractory wall 13.

Referring now to FIGS. 3(a)-(c), long refractory block 111 is shown ingreater detail. As can be seen, refractory block 111 is precast as aunitary, modular component. Preferably, block 111 is precast using anysuitable heat-resistant material, such a concrete mixture. As can beappreciated, the precast construction of block 111 ensures dimensionalaccuracy as well as material consistency (e.g., eliminating the presenceof bubbles), which is not readily obtainable in traditionalcast-in-place constructions.

Block 111 is solid, brick-like member with a slight, yet consistent,radial curvature and includes a flat top surface 113, a flat bottomsurface 115, an arcuate inner surface 117, an arcuate outer surface 119,a flat left end surface 121, and a flat right end surface 123.Dimensionally, block 111 preferably has a uniform width W₁ ofapproximately 9 inches, a uniform height H₁ of approximately 6.4375inches, and extends in length along an arc A₁ of approximately 20degrees to yield an inner arc length L_(I1) of approximately 11.375inches and an outer arc length L_(O1) of approximately 14.5 inches.However, it is to be understood that the block 111 is not limited to theaforementioned dimensions and could be resized, as needed, withoutdeparting from the spirit of the present invention.

A projection 125, semi-circular in transverse cross-section, protrudesupward from top surface 113 along its centerline. Additionally, a recess126, semi-circular in transverse cross-section, is formed in bottomsurface 115 along its centerline. Both projection 125 and recess 126have a radius of approximately 1 inch and thereby serve as complementarysurface mating features, as will be described further below.

Projection 125 extends along the majority of the length of block 111,with projection 125 extending just beyond left end surface 121 to form atongue 127. Tongue 127 extends vertically across left end surface 121and is generally semi-circular in cross-section, as seen most clearly inFIG. 3(c). A complementary groove 129, generally semi-circular incross-section extends vertically in right end surface 123, with groove129 having the same radius as tongue 127.

In this manner, it is to be understood that multiple blocks 111 areadapted to be stacked directly upon one another, with projection 125 ofa lower block 111 protruding into recess 126 in an upper, or stacked,block 111. In this manner, this interlocking arrangement betweenprojection 125 and recess 126 serves not only to facilitate properregistration between a stacked pair of blocks 111 but also to providestructural support and thereby minimize the risk of inner walldestabilization over time.

Similarly, it is to be understood that multiple blocks 111 are adaptedto be configured in an end-to-end relationship, with tongue 127 of oneblock 111 protruding into groove 129 in an adjacent, or neighboring,block 111. This interlocking arrangement between tongue 127 and groove129 also serves to facilitate proper registration between an adjacentpair of blocks 111 and provide structural support to inner refractorywall 13, which is highly desirable.

As referenced above, the dimensions of block 111 could be readilymodified without departing from the spirit of the present invention.Most notably, arc A₁ of block could be adjusted to provide the designerof inner refractory wall 13 with greater flexibility in its structuralconfiguration.

As an example, in FIGS. 4(a)-(c), short refractory block 131 is shown ingreater detail. As can be seen, short refractory block 131 is identicalto refractory block 111 in that short refractory block 131 is precast asa unitary, modular component using any suitable heat-resistant material,such a concrete mixture.

Refractory block 131 is also identical to refractory block 111 in thatrefractory block 131 is constructed as solid, brick-like member with aslight, yet consistent, radial curvature and includes a flat top surface133, a flat bottom surface 135, an arcuate inner surface 137, an arcuateouter surface 139, a flat left end surface 141, and a flat right endsurface 143.

As further similarities, a projection 145, semi-circular in transversecross-section, protrudes upward from top surface 133 along itscenterline and mates with a semi-circular recess 146 formed in bottomsurface 135 along its centerline. Additionally, a tongue 147,semi-circular in transverse cross-section, extends vertically acrossleft end surface 141 and mates with a complementary groove 149 extendingvertically in right end surface 143.

Refractory block 131 only differs from refractory block 111 in itsdimensions. Although refractory block 131 has a uniform width W₂ ofapproximately 9 inches, which is identical to refractory block 111, anda uniform height H₂ of approximately 6.4375 inches, which is identicalto refractory block 111, refractory block 131 is considerably shorter inlength than refractory block 111.

Notably, refractory block 131 extends in length along an arc A₂ ofapproximately 10 degrees to yield an inner arc length Lie ofapproximately 5.6875 inches and an outer arc length L_(O2) ofapproximately 7.25 inches. As such, refractory block 131 is one-half thelength of refractory block 111.

As another example, in FIGS. 5(a)-(c), medium-length refractory block151 is shown in greater detail. As can be seen, medium refractory block151 is identical to refractory block 111 in that medium refractory block151 is precast as a unitary, modular component using any suitableheat-resistant material, such a concrete mixture.

Refractory block 151 is also identical to refractory block 111 in thatrefractory block 151 is constructed as solid, brick-like member with aslight, yet consistent, radial curvature and includes a flat top surface153, a flat bottom surface 155, an arcuate inner surface 157, an arcuateouter surface 159, a flat left end surface 161, and a flat right endsurface 163.

As further similarities, a projection 165, semi-circular in transversecross-section, protrudes upward from top surface 153 along itscenterline and mates with a semi-circular recess 166 formed in bottomsurface 155 along its centerline. Additionally, a tongue 167,semi-circular in transverse cross-section, extends vertically acrossleft end surface 141 and mates with a complementary groove 169 extendingvertically in right end surface 163.

Refractory block 151 only differs from refractory block 131 in itsdimensions. Although refractory block 151 has a uniform width W₃ ofapproximately 9 inches, which is identical to refractory block 111, anda uniform height H₃ of approximately 6.4375 inches, which is identicalto refractory block 111, refractory block 151 is considerably shorter inlength than refractory block 111 but greater in length than refractoryblock 131.

Notably, refractory block 151 extends in length along an arc A₃ ofapproximately 16 degrees to yield an inner arc length L_(I3) ofapproximately 9.125 inches and an outer arc length L_(O3) ofapproximately 11.625 inches. As such, the length of refractory block 151lies between the lengths of refractory blocks 111 and 131.

Referring now to FIGS. 6(a)-(e), tuyere refractory block 171 is shown ingreater detail. As will be explained further in detail below, each block171 is precast to define a single tuyere hole, or airflow nozzle, 31.Due to the precast nature of block 171, the exact position, dimensions,and angle of orientation of airflow nozzle 31 can be ensured with greatprecision. As a result, combustion cell 11 is more effective insustaining efficient and balanced combustion of waste products.

By contrast, the conventional practice of creating tuyere holes byramming and subsequently removing cylindrical sleeves into a one-piece,curable, refractory lining has been found to be difficult to implementwith great precision. As a result, airflow nozzles are often arrangedand formed in conventional refractory linings with widespread variancesand inconsistencies, which is highly undesirable.

As can be seen, tuyere refractory block 171 is identical to refractoryblock 111 in that refractory block 171 is precast as a unitary, modularcomponent using any suitable heat-resistant material, such a concretemixture.

Refractory block 171 is also identical to refractory block 111 in thatrefractory block 171 is constructed as solid, brick-like member with aslight, yet consistent, radial curvature and includes a flat top surface173, a flat bottom surface 175, an arcuate inner surface 177, an arcuateouter surface 179, a flat left end surface 181, and a flat right endsurface 183.

As further similarities, a projection 185, semi-circular in transversecross-section, protrudes upward from top surface 173 along itscenterline and mates with a semi-circular recess 186 formed in bottomsurface 175 along its centerline. Additionally, a tongue 187,semi-circular in transverse cross-section, extends vertically acrossleft end surface 181 and mates with a complementary groove 189 extendingvertically in right end surface 183.

The exterior dimensions of refractory block 171 are also identical torefractory block 111. In fact, block 171 only differs from refractoryblock 111 in its inclusion of tuyere hole 31. As can be seen, tuyerehole 171 is in the form of a tubular bore with a circular cross-sectionof uniform diameter D along its length, diameter D preferably beingapproximately 1.375 inches.

Tuyere hole 31 is designed to extend in a downward and right-to-leftdirection from outer surface 179 to inner surface 177, with one end 31-1located in the corner of outer surface 179 proximate top surface 173 andright end surface 183 and the other end 31-2 located in the corner ofinner surface 177 proximate bottom surface 175 and left end surface 181.Preferably, tuyere hole 31 is pitched so as to extend at a downwardangle Θ₁ of approximately 15 degrees and a right-to-left, or horizontal,angle Θ₂ of approximately 45 degrees. As can be appreciated, thedimension and orientation of tuyere hole 31 is optimized to deliver anefficient and balanced airflow supply into combustion zone 19.

Referring now to FIGS. 7 and 8, tieback refractory block 191 is shown ingreater detail. As will be explained further in detail below, eachtieback block 191 is uniquely designed to facilitate its securement to afixed support structure. As a result, the inclusion and fixed securementof tieback blocks 191 provides anchored structural support to inner wall13 so as to minimize the risk of destabilization over time.

As can be seen, tieback refractory block 191 is identical to refractoryblock 111 in that tieback refractory block 191 is precast as a unitary,modular component using any suitable heat-resistant material, such aconcrete mixture.

Tieback refractory block 191 is also identical to refractory block 111in that refractory block 191 is constructed as solid, brick-like memberwith a slight, yet consistent, radial curvature and includes a flat topsurface 193, a flat bottom surface 195, an arcuate inner surface 197, anarcuate outer surface 199, a flat left end surface 201, and a flat rightend surface 203.

As further similarities, a projection 205, semi-circular in transversecross-section, protrudes upward from top surface 193 along itscenterline and mates with a semi-circular recess 206 formed in bottomsurface 195 along its centerline. Additionally, a tongue 207,semi-circular in transverse cross-section, extends vertically acrossleft end surface 201 and mates with a complementary groove 209 extendingvertically in right end surface 203.

The exterior dimensions of refractory block 191 are also largelyidentical to refractory block 111. However, block 191 differs fromrefractory block 111 in that block 191 is shaped to include an externalgroove, or recess, 211 which is suitably dimensioned to receive anL-shaped tie-back 213. As will be explained further below, tie-back 213is designed for fixed securement to a support structure in order tostabilize inner wall 13.

As can be seen, external groove 211 is generally circular in transversecross-section and has a uniform diameter of approximately 0.5 inches.External groove 211 is generally L-shaped and includes (i) a horizontalportion 211-1 formed in top surface 193 which extends radially inwardfrom outer surface 199 at its approximate midpoint, and (ii) a verticalportion 211-2 which extends orthogonally downward from the inner end ofhorizontal portion 211-1, vertical portion 211-2 extending down from topsurface 193 towards bottom surface 195 for a depth of approximately 3inches.

External groove 211 in block 191 is designed to retain a correspondingtie-back anchor, or tie-back, 213. Tie-back 213 is constructed as aunitary, L-shaped rod constructed of a rigid and durable material, suchas stainless steel. In the present embodiment, tie-back 213 has auniform diameter of 0.5 inches and includes a horizontal segment 213-1and a vertical segment 213-2 extending at a right angle.

As shown in FIG. 8, tie-back 213 is designed for fitted insertion inexternal groove 211, with horizontal segment 213-1 of tie-back 213 lyingwithin horizontal portion 211-1 in block 191 and vertical segment 213-2of tie-back 213 projecting within vertical portion 211-2 in block 191.Mounted into engagement as such, the distal end of horizontal segment213-1 of tie-back 213 protrudes beyond outer surface 199 of block 191.

A vertical support tube 221 extending in abutment against outer surface199 of block 191. In the present embodiment, tube 221 is represented asan elongated tubular member, constructed of a rigid and durablematerial, with a 2-inch square shape in transverse cross-section. As afeature of the invention, the distal end of tie-back 213 preferablyaligns flush against a side surface of tube 211. Therefore, by directlywelding tie-back 213 to side surface of tube 211, block 191 (andeffectively all other blocks connected thereto) is provided rigidanchored support from tube 221.

Design and Assembly of Inner Wall 13

Referring back to FIGS. 1(a)-(c), inner wall 13 of combustion chamber 11is preferably constructed, at least in part, in the following manner.First, prior to assembly, a plurality of support tubes 221 are arrangedin a circular configuration so as to define the outer diameter of innerwall 13. Tubes 221 extend vertically and are preferably welded, orotherwise fixedly secured to, outer wall 15.

As seen most clearly in FIG. 1(c), tubes 221 are preferably spacedevenly apart from one another so as to provide uniform support for innerwall 13. In the present embodiment, eighteen tubes 221 are spaced apartat 20-degree intervals. As such, the requisite number of evenly-spacedtieback blocks 191 in each layer (e.g. nine tieback blocks 191) is ableto anchor onto a corresponding set of tubes 221.

With support tubes 221 installed, the design of inner wall 13 isformulated using refractory block set 101. The particular selection andarrangement of blocks 111, 131, 151, 171, and 191 utilized to constructinner wall 13 as a complete sealed ring are determined based on, interalia, the desired dimensions, structural needs, and airflow requirementsof combustion unit 11.

Once design of inner wall 13 is formulated, the selection of refractoryblocks from set 101 are stacked, layer by layer, in the predeterminedarrangement, with the interlocking mating faces of adjacent refractoryblocks not only facilitating proper registration but also providingenhanced structural support, as shown in FIGS. 9 and 10. The four-sidedinterlocking of each refractory block with its neighboring blocks alsoenables the interior surface of inner wall 13 to wear away by nearlyhalf of its thickness without disruption to the intermating featureestablished between adjacent surfaces. As part of the assembly process,all other essential components of combustion unit 11 (e.g., outlet 21,grate 23 access port 25, chute 27) are properly integrated into innerwall 13 during the stacking of the selection of refractory blocks 111,131, 151, 171 and/or 191.

Preferably, a refractory mortar (not shown) is preferably applied in thejoint, or spacing, between adjacent blocks for bonding purposes in orderto create a uniform interior surface and ensure structural integrity.Preferably, a thin, uniform layer of the mortar (e.g., approximately0.0625 inches in thickness) is applied to effectuate bonding withoutdistorting proper positioning.

Ideally, a predefined number of tieback blocks 191 are utilized in eachlayer, with variability in the location and/or number of tieback blocks191 created through selection amongst the different lengthened blocks111, 131 and 151. Tieback blocks 191 are therefore preferably arrangedfor welding to corresponding tubes 221 by tie-backs 213. As a feature ofthe invention, the welding of tieback blocks 191 to support tubes 221eliminates the need for the expanded metal support utilized intraditional combustion units and thereby remedies the variousshortcomings associated therewith.

As seen in FIG. 1(c), each layer of inner wall 13 preferably secures atieback block 191 to a first set of alternating (i.e. every other)support tubes 221, with adjacent layers of wall 13 preferably securing atieback block 19 to the remaining (i.e. second set) of alternatingsupport tubes 221. In this fashion, support to inner wall 13 isuniformly distributed.

Additionally, a predefined number of tuyere blocks 171 is preferablyutilized and equidistantly arranged in each layer to provide thenecessary secondary airflow required to optimize combustion withininterior cavity 19. By ensuring balanced and efficient combustion withinunit 11, any degradation of inner wall 13 is greatly minimized.Furthermore, because blocks 171 are precast, the shape and dimension ofeach tuyere hole 31 is formed with considerable precision.

As can be appreciated, the construction of inner wall 13 using aplurality of precast refractory blocks improves its overall structuralintegrity and manufacturing precision. As an additional benefit, themodular nature of inner wall 13 allows for sections thereof to be simplyand easily restored using replacement refractory blocks, as needed.

The invention described in detail above is intended to be merelyexemplary and those skilled in the art shall be able to make numerousvariations and modifications to it without departing from the spirit ofthe present invention. All such variations and modifications areintended to be within the scope of the present invention as defined inthe appended claims.

What is claimed is:
 1. A combustion chamber for the incineration ofwaste products, the combustion chamber comprising: (a) an outerprotective wall; and (b) an inner refractory wall extending within theouter protective wall, the inner refractory wall being shaped to definean interior cavity; (c) wherein the inner wall comprises a plurality ofprecast, refractory blocks.
 2. The combustion chamber of claim 1 whereinthe inner refractory wall is spaced in from the outer protective wall soas to define a plenum therebetween.
 3. The combustion chamber of claim 2wherein the plurality of precast, refractory blocks is stacked in layersand together, at least in part, define the interior cavity.
 4. Thecombustion chamber of claim 3 wherein the plurality of precast,refractory blocks matingly engages one another when stacked in layers.5. The combustion chamber of claim 3 wherein each of the plurality ofprecast, refractory blocks comprises a top surface, a bottom surface, aninner surface, an outer surface, a left end surface and a right endsurface.
 6. The combustion chamber of claim 5 wherein the inner surfacefor each of the plurality of precast, refractory blocks has a fixedradial curvature.
 7. The combustion chamber of claim 5 wherein aprojection is formed on the top surface of each of the plurality ofprecast, refractory blocks.
 8. The combustion chamber of claim 7 whereina recess is formed on the bottom surface of each of the plurality ofprecast, refractory blocks.
 9. The combustion chamber of claim 8 whereinthe recess on one of the plurality, of precast, refractory blocks isdimensioned to fittingly receive the projection on another of theplurality of precast, refractory blocks when arranged in a stackedrelationship.
 10. The combustion chamber of claim 5 wherein a tongueextends out from one of the left end surface and the right end surfaceof each of the plurality of precast, refractory blocks.
 11. Thecombustion chamber of claim 10 wherein a groove is formed in the otherof the left end surface and the right end surface of each of theplurality of precast, refractory blocks.
 12. The combustion chamber ofclaim 11 wherein the groove on one of the plurality, of precast,refractory blocks is dimensioned to fittingly receive the tongue onanother of the plurality of precast, refractory blocks when arranged inan end-to-end relationship.
 13. The combustion chamber of claim 5wherein at least two of the plurality of precast, refractory blocksdiffer in length.
 14. The combustion chamber of claim 5 wherein at leastone of the plurality of precast, refractory blocks is shaped to define atuyere hole.
 15. The combustion chamber of claim 14 wherein the tuyerehole is circular in transverse cross-section.
 16. The combustion chamberof claim 15 wherein the tuyere hole extends downward and horizontallyfrom the outer surface to the inner surface.
 17. The combustion chamberof claim 5 further comprising a vertical support tube fixedly coupled tothe outer protective wall.
 18. The combustion chamber of claim 17wherein at least one of the plurality of precast, refractory blocks issecured the vertical support tube with a tie-back anchor.
 19. Thecombustion chamber of claim 18 wherein the at least one of the pluralityof precast, refractory blocks is shaped to define a groove which isdimensioned to fittingly receive at least a portion of the tie-backanchor.